Centralized traffic controlling system for railroads



July 18, 1939. R. F. WELLS CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed May 27, 1937 t3 55 SSG/PB., mm a. @l

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E15 T 2056EA JUG MCCC m n oF JQ I @@.Nm msm@ Xin@ Patented July 18, 1939 PATENT OFFICE CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Robert F. Wells, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application May 27, 1937, Serial No. 145,070

16 Claims.

This invention relates to centralized traffic controlling systems for railroads and it more particularly pertains to a means for registering and checking control codes in a communication system of the multiple impulse or coded type.

Inthe multiple impulse or coded type communication system commonly employed in centralized traffic controlling systems Vfor the purpose of governing the operation of switchesand signals at a distant eld station from a central control office, the controls for governing the operation of the switches -and signals are transmitted by a series of time spaced (-H or impulses, or impulses otherwise characterized by variable line circuit conditions, or the like. Y

The distinctive control impulses are employed lto condition suitable relays at the field station for governing the operation of power operated track switches and the conditions of their associated signals. In one arrangement, such as disclosed in the prior application of T. J. Judge et al., Ser. No. 640,062, now U. S. Patent 2,082,544, granted June 1, 1937, corresponding to British 'Patent No. 419,399, the character of the control impulse for each step is determined by positive and negative control relays, identified as PC and NC relays in the above mentioned prior application.

In such an arrangement, a control impulse for operating a control relay fromits existing condition to another desired condition may not be effective, dueto a broken wire, bad contact, or the like, with the result that the desired control actually transmitted and received at the field station is not properly registered. While the system for controlling the switches and signal is so organized that no unsafe condition is produced by such a failure, trains may be signalled to advance over a Wrong route not desired by the operator.

In a particular arrangement for registering controls, such as disclosed, for example, in my prior application, Ser. No. 634,370, filed September 22, 1932, neutral decoding relays, all deenergized at the beginning of a transmitting cycle, are selectively energized in accordance with the control code transmitted and then the relays controlling the switches and signals are conditioned, provided the decoding relays have properly responded to the control code transmitted.

i This arrangement requires decoding relays, two

for each step, in addition to the switch and signal control relays.

One object of this invention is to provide an improved arrangement over the arrangement disclosed in my prior application, Ser. No. 634,370, in

that means are provided for registering the code character of the control impulses which is reliable in its operation, does not require the use of additional'decoding means and which checks the response of the control relays to the code de- 5 livered on each step.

Generally speaking, and by Way of explanation and without attempting to define the nature or scopeof the present invention, it is proposed to employ a polarswitch control relay and neutral 10 stick control relays, directly responding in succession to the character of the control impulses for the successive steps, these relays individually or jointly controlling the operation Yof the switches and signals. It is further proposed to 15 provide a'checking relay which must be energized before the signal control relays can be picked up and with the circuit organization so arranged that the response of the signal control relays is checked in a manner which will be described in 2O detail.

' Other characteristic features, attributes and advantages of the organization of relays and circuits constituting the present invention will be in part apparent and in part pointed out as the 25 description progresses.

The present invention relates only to a part of a complete system of code communication for centralized trafc control and while it is contemplated that the invention Will be used with 30 the various'features commonly employed or suitable for such a complete system, such as station selection, transmission of indications, and the like, in order to simplify the disclosure and facilitate in the explanation, such features of the 35 complete system are not illustrated and will not be disclosed, except in a general Way and in so far as appears to be desirable for an understanding of the functions and mode of operation of the parts and circuits constituting this par- 40 ticular improvement.

The accompanying drawing illustrates diagrammatically one form of the present invention. For the purpose of simplifying the illustration, the various relays and circuits have been shown 45 conventionally and symbols and have been employed to indicate connections to the opposite terminals of a battery or other suitable source of current, instead of showing all of the Wiring connections that would be employed in 50 practice.

Referring to the drawing, the control office portion of the complete system is merely indicat-ed by the dotted rectangle in the left hand portion of the drawing, containing the legend 55 control office. The code transmitting and receiving equipment in the control oiice is connected to the equipment at the Various field stations, it is assumed, by three line wires, comprising a stepping and control line wire SCL, an indication line wire IL and a common return line wire CL. The stepping and control line wire SCL, is used in combination with common return wire CL to constitute a stepping and control line circuit, to which a series of polar impulses are applied in the control oiiice for sequentially operating stepping relays at the field station and for conditioning control relays for governing the operation of switches, signals and the like.

For the purpose of explaining and understanding the present improvement, it is considered unnecessary to illustrate the code transmitting equipment in the control oiiice, by means of which these series of impulses are applied to the stepping and control line circuit.

Appaatus.-Relay F is the line relay connected in series with the stepping and control line at the illustrated field station for repeating the impulses applied to this line. By means of polar contact I I, line repeating relay FP repeats the operations of line relay F. By means of front contact I3 of relay FP, slow acting relay SA is picked up at the beginning of each cycle, is held up throughout the cycle and is released during the clearout period at the end of the cycle. By means of front contact 2i) oi relay SA, relay SB is likewise picked up at the beginning of the cycle and is not released until the end of the cycle.

Station selecting relay SO is illustrated, without its control circuits being shown, for the purpose of indicating how controls are transmitted to the control relays at the various steps of a cycle, in accordance with the polarity oi the impulses applied to the line circuit, such controls only being effective at a selected station, at which the associated SO relay is picked up. The means of providing this station selection feature is not believed material to an understanding of the present invention, since this may be brought aboutrin the same manner illustrated in the above mentioned Judge et al. application.

A group or bank of stepping relays, comprising half-step relay VP and stepping relays IV, 2V, 3V, and the like, is provided at each eld station for selecting local channel circuits. Relay WZ is the switch control relay and is of the polar, magnetic stick type, maintaining its polar contacts in their last actuated positions after the relay has been deenergized. Neutral right direction stick control relay RD and neutral left direction stick control relay LD are provided for governing the clearing of the signals associated with the illustrated track section.

Relay EX is an executing relay provided for the purpose of holding oli execution of the transmitted controls until they have all been received, the circuit for controlling such a relay not being illustrated, since it may be controlled in the same manner as illustrated in the prior application of W. D. Hailes et al., Ser. No. 11,090, led March 14, 1935, new U. S. Patent 2,090,912, granted August 24, i937. Stop relay S is provided for illustrating how signals at the iield station are put to stop in response to the stop code, as will be described in detail. Resistance IR connected in multiple with the lower winding of relay CK and resistance 2R connected in multiple with the winding of relay S are for the purpose of rendering these relays slightly slow releasing. Relay CK is the checking relay provided for the purpose of obtaining the checking feature which forms an important objection of the present invention. Relays T and TP are the usual track and track repeater relays.

The circuit organization and the mode of operation of the stepping relay bank is explained in detail in the above mentioned Judge et al. application and since the particular mannerv of operating the stepping relay bank constitutes no part of the present invention, it will be sufcient to merely point out certain characteristic features and the times at which the relays of the stepping relay bank are operated to various positions.

During the conditioning period at the beginning of a control cycle, for example, relays F, FP, SA and SB are picked up, whereupon relay VP is picked up and stuck up until the next on period, when it is released. Relay VP is thereafter picked up and released during alternate on periods.

When the line circuit is opened at the end of the conditioning on period and relays F and FP are deenergized, the iirst stepping relay IV is picked up and stuck up. When the line circuit is next energized, relay VP releases, as above pointed out, relay IV now being up. During the next deenergization of the line circuit, the next stepping relay 2V is picked up and stuck up and during the next energization oi the line circuit, relayVP again picks up, as above pointed out, to prepare the energizing circuit for the next stepping relay 3V. This same operation is repeated for as many steps as desired, with relay EX being picked up during the last deenergization of the line circuit for executing the received controls.

Thus, in accordance with the particular arrangement of stepping relays assumed for the specic embodiment of the invention illustrated in the drawing, after relay VP is initially energized during the rst energization of the line circuit (conditioning onr period), a stepping relay picks up during each succeeding deenergization of the line (off period) and relay VP changes from its picked up or its released condition, as the case may be, during each of the succeeding energization or on periods.

This sequential operation of lthe stepping relay bank selects local channel circuits for energizing the local control relays WZ, RD, LD and S 1n accordance with the polarity of energization of the 1' line relay F, during an on period following the off period during which the stepping relay was picked up.

Reception of control codes-Considering now the sequence of operations and referring to the drawing for explanatory purposes, it will be assumed that the line and line repeated relays are operated as above described and that the stepping relay bank operates through a cycle, during which three off and three on periods are provided for receiving code combinations applied to the communication system in the control oice. At the end of the cycle, during the clearing out period it will be assumed that relay EX ispicked up in response to the release of relay FP, after which relays SA and SB release, followed by the release of the stepping relays and the EX relay. It will further be assumed that station relay SO is picked up at the beginning of the cycle, maintained picked up throughout the cycle and released in response to the release of relay SB at the end of the cycle. l

Code ).-It will be assumed that the oiiice applies this code to the line circuit for operating the switch to normal and for clearing 75 tact 25 of relay F in its right hand dotted-posi-` tion, back contacts 26 and '21 o f relays 3V andl 2V, front contact 28 of relay IV, lower winding of relay WZ, back contact 3| of relay RD andV back contact 32 of relay LD, to Current in this direction .through the lower winding of relay WZ positions its polar contacts to the right for controlling the normal energizing circuitV of the switch machine at contact 33.

In the event that relay WZ is already positioned to the right, or after its polar contacts are positioned to the right in response tothis (-1-) impulse, a circuit is closed for 'picking up relay CK, including that previously described up to and including front contact 28, and thence through contact 34 of relay WZ in its right hand position, back contact 35 of relay RD, back contact 35 of relay LD and lower winding of relay CK, to Relay S is now picked up over an obvious circuit closed at front contact 31 of relay CK.

When relay F releases at the end of the rst on period, relay CK remains energized for a short time interval, due to its slow acting charactezistics provided by resistance IR connected in shunt with its lower winding. Then when relay FP releases, in response to the release of relay F, a i'lrst stick circuit is'closed for relay CK extending from (-1-), front contact 38 of relay SA, back contact 39 of relay FP, front contact 48 and upper winding of relay CK, to

When relay F is energized in response to the second impulse, relay RD is picked up over a circuit extending from (-1-), front contact 30 of relay SO, contact 25 of relayF in its right hand dotted position, back contact 26 of relay 3V, front contact 21 of relay 2V, back contact 4| of relay LD, upper winding of relay RD and front contact 42 of relay CK, to Relay RD is stuck up over a circuit extending from (-1-), iront contact 43 of relay CK, front Vcontact 44 and lower winding of relay RD, to The iirst stick circuit for relay CK is opened when relay FP picks up and opens its back contact 33, but before relay CK releases, a second stick circuit is closed for this relay which extends from (-1-), front contact 30 of relay SO, contact 25 of relay F in its right hand dotted position, back contact 28 of relay 3V, front contact 21 of relay 2V, back contact 4| of relay LD, front contact 45 of relay RD, front contact 46 and lower winding of relay CK, to

At the end of the second on period, the release of relay F opens the above described second stick circuit for relay CK but, due to its slow acting characteristics, this relay is not released and its rst stick circuit is completed as previously described, which extends through` back contact 39 of relay FP.

At the beginning of the third on period, .the second stick circuit for relay CK is again cornpleted, but which now extends from (-1-), front contact 3Q of relay SO, contact 25 of relay F in its left hand dotted positionv (because the third impulse is front contact 41 of relay 3V, back contact 48 of relay LD, front contact 46 and lower winding of relay CK, to and this stick circuit is completed before the first stick circuit is opened by the picking up of relay FP.

During the clearing out period, the release of relay F opens the above described second stick circuit for relay CK at contact 25, but before this relay has time to release, its rst stick circuit is closed at back contact 39 of relay FP. The release of relay SA during the clearing out period deenergizes the rst stick circuit for relay CK at front contact 38, effecting the release of relay CK and because of open front contact 31, relay S is released.

As above mentioned, relay WZ last actuated position, because of its construction, so that it is not necessary to maintain its;

windingV energized. Relay RD remains stuck up over the previously described circuit completed' at front contact 43 of relay CK, until relay CK releases in the clearing out period. Before the release of relay CKhoWever, another stick circuit is closed for relay RD extending from (-1-), back contact 49 of relay SA, front contact 58 of relay SO, front contact 5| of relay iront contact 44 and lower winding of relay RD, to This stick circuit is broken when relay SO releases in response to the release of relay SB, but before this happens a permanent stick circuit is completed for relay RD extending from (-1-), front contact 52 of relay T, back contact 54 of relay S, back contact 43 of relay CK, front contact 44 and lower winding of relay RD, to'( This permanent stick circuit for relay RD is maintained completed until the train enters the illustrated track section, drops relay T and interrupts the stick circuit at contact 52, thus `allowing relay RD to release, after which relay TP releases and applies (-1-) to the RD- LD stick circuits at back contact 53, so that energy will remain on these stick circuits until the track sponse to the occupancy of the illustrated trackv section, as above mentioned, opens the above described signal clearing circuit for putting the signals to stop. As will be later described, a cleared signal is also put to stop in response to the receipt of a stop code. v

Code (-1) ).-This code controls the operation of the track switch to its reverse direc-- tion by positioning contact 33 of relay WZ tothe left in response to the first impulse, which co-mpletes a circuit for relay WZ extending from (-1), front Contact 30 of relay SO, contact 25 of relay F in its left hand dotted position, back contact 41 of relay 3V, back contact 5S of relay 2V, front contact 59 of relay IV, upper winding of relay WZ and back contacts 3| and 32 of relays RD and LD, to The energization of the upper winding of relay WZ is opposite to that previously described through its lower winding, so that its polar contacts are positioned to the left,

after which a similar circuit to that previouslyV described, is closed at contact 34 in its left hand dotted position for picking up relay CK. Relay remains in its cui the left.

open back contact 3l of relayv RD. The second impulse closes a circuit for picking up relay S extending from (-1-), front contact 30 of relay SO, contact 25 of relay F in its left hand dotted position, back contact 41 of relay 3V, front contact 58 of relay 2V, front contact 29 of relay RD, back contact 31 of relay CK and winding of relay S, to The opening of back contact 54 of relay S opens the stick circuit of relay RD, Whereby this relay is released and the cleared signal is put to stop because of open front contact 56. It will be understood that the opening of back contact 54 of relay S would also release relay LD, if this relay were stuck up. At the end of the second on period, the release of relay F effects the release of relay S because of open contact 25. The third impulse is: ineffective, since the circuit through front contact 4l' of relay 3V is incomplete at open front contacts 24 and 48 of relay LD and at open front contacts 29 and 45 of relay RD.

Code This code is effective to put a cleared signal to stop in the same manner as the one just previously described. The first impulse is ineffective because of open back contacts 3| and 35 of relay RD (or back contacts 32 and 36 of relay LD)., It will be understood that the first impulse ((-1-) or in a stop code may be used to position the track switch, without clearing a signal, when no signal is cleared at the beginning of such a` code. combination.

Code (-1-) (-1-).-This code is for the purpose of actuating the track switch to its normal position and for clearing the signal for trafiic to The first (-1-) impulse controls relays WZ, CK and S in the same manner described in connection with code (-1-) during the first on period and the second oif period. During the second on period the impulse applied to the line positions relay F to the left for completing the second stick circuit for relay CK, before the first stick circuit is opened at back contact 39 of relay FP, and which extends from (-1-), front contact 30 of relay SO, Contact 25 of relay F in its left hand dotted position, back contact 41 of relay 3V, front contact 58 of relay 2V, back contact 45 of relay RD, front contact 46 and lower winding of relay CK, to

At the beginning of the third off period, the release of relay F opens the above described second stick circuit for relay CK and (due to the slow acting characteristics; of relay CK) before this relay releases its first stick circuit is completed at back contact 39 of relay FP.

During the third on period, before relay CK can release in response to the opening of back contact 39 of relay FP, its second stick circuit is closed by the picking up of relay LD, which stick circuit extends from (-1-), front contact 3D of relay SO, contact 25 of relay F in its right hand dotted position, front contact 26 of relay 3V, back contact 23 of relay RD, front contact 48 of relay LD (picked up as will be described), front contact 46 and lower Winding of relay CK, to Relay LD is picked up during the third on period over the above described circuit through back contact 23 of relay RD, upper winding of relay LD and front contact 42 of relay CK, to

Relay LD is stuck up over an obvious circuit closed at its front contact 22, until relay CK releases to open this stick circuit at front contact 43. Before this stick circuit is opened however, the executing stick circuit for relay LD is completed by the release of relay SA and extends through front contact I of relay EX, as previously described, front contact 22 and lower winding of relay LD, to Before this executing stick circuit is broken, the permanent stick circuit forrelay LD is completed at back contact 54 ofrrelay S, which circuit will be obvious from that previously described for relay RD. Relay CK is stuck up during the clearing out period as previously described, until relay SA releases and opens its stick circuit at front contact 38.

With the switch in its normal position and with the circuits properly lined up by the position of this switch, the signal for governing trafc to the left is energized over a circuit extending from (-1-), back contact 55 of relay CK, front Contact 2| of relay LD and over conductor 60 to the circuits which control the selected signal.

Code (-1-) .-This code is similar to that just previously described and controls the CK, S and LD relays in the same manner as previously described. The first impulse is instead of (-1-), therefore relay WZ is actuated to the left for controlling the switch to its reverse position.

It will thus be seen that the circuits make use of a single checking relay for checking the response of the switch control relay and the executing of signal controls, Without the use of separate decoding relays controlled at each step. Relay CK is picked up during the first on period, through a circuit extending through back contacts of the RD and LD relays and a contact of relay WZ in its right hand position (if the first impulse is (1-)) and through a contact of relay WZ in its left hand position (if the first impulse is thus first checking that no signal is clear and thereafter checking that relay WZ has responded to the transmitted code. During the ofi and on periods of the second and third steps, the response of the LD and RD relays are checked in a like manner, by maintaining relay CK energized during the steps only as the signal control relays properly respond. Furthermore, a check of the receipt of the proper number of steps is provided, since relays RD and LD depend upon relay CK being energized for completing the RD and LD pick up circuits: and when these signal control relays are once picked up they stick up over a. front contact of relay CK until the executing circuit is completed, which bridges or overlaps the release of relay CK and relay S, to

make up the permanent stick circuit for the RD or LD relays.

It Will be understood that codes (-1-) (-1-) (-1-) and (-1-) (-1-) are not used in connection with the control codes of the present embodiment, or

these codes may be used for other purposes, such iai: a call-on signal, maintainers signal, or the Various adaptations and modifications may be made in the particular arrangement of devices and circuits shown and described as exemplifying the invention, Without departing from the fundamental functions and advantages of the invention; and means for receiving or registering controls in a centralized traiiic controlling system, in accordance with this invention, may be employed in conjunction with various other features of a complete system.

What I claim is:

1. In a remote control system of the multiple impulse or code type including an instrumentality for registering controls transmitted to govern the operation of variable position devices comprising, line wires for transmitting a series of code conditions each controllable in character, step-by-step meanszoperable to take one step for each code condition, a rst neutral control relay having a pick up circuit energized or left deenergized dependent onthe character of a code condition, a second neutral control relay having a pick up circuit energized or left deenergized dependent on the `character oi another code condition, a checking relay acting ii deenergized to break said pickup circuits, stick circuits controlled by said checking relay for maintaining said control relays stuck up when picked up, means for picking up said checking relay, a iirst stick circuit for said checking relay closed while said step-by-step means is being operated for each step, and a second stick circuitffor said checking relay closed after each step only if said control relay for that step assumes a condition in proper correspondence with the character of the corresponding code condition transmitted.

2. Ina remote control system Aof the multiple impulse or code type including an instrumentality for registering controls transmitted to govern the operation of variable position devices comprising, line Wires for transmitting a series o code conditions each controllable in character, step-bystep means operable to take one step for each code condition, a first neutral control relay associated withone step and having a pick up circuit energized or left deenergized dependent on the character ofthe code condition for that step, a second neutral control relay associated with another step and having a pick up circuit energized or left deenergized depending on the character of the code conditionfor that step, a checking relay controlling said pick-up circuits, stick circuits controlled by said checking relay for maintaining said `control relays stuck up when picked up, means for picking up said checking relay, a first stick circuit for said checking relay closed While said` step-by-step means is being operatedHfor-each step, a. secondstick circuit for said checking` relay closed between steps only if `said relays in turn are in` proper correspondence .means responsive tothe operation of said stepby-step means for-the proper number of steps for `temporarily.sticking up an energized control relay during the release of said checking relay, and ,other stick` circuit means for said control relays rendered eiective upon the release of said checking relay. l l,

3. Ina: centralized traiiic controlling system for governing the operation of signals associated with a track switch at a distant field station from a control omce, a stepping and control line circuit extending from said oiiice to said station, a neutral relay responsive to the energization of said line circuit irrespective of the polarity oi such -energizatiom aseries of stepping relays controlled bysaidneutralrelay and energized sequentially, a polar line relayin said line circuit, two neutral signal control relays respectively governing the clearing oflsignals in opposite directions over the track switch, an energizing circuit for each of said signal control relays including a contact of a particular vstepping relay and a contact of said polar line relay, achecking relay having a front contact included in said energizing circuits, means for energizing said checking relay, stick circuits for said signal control relays closed when said checking relay is energized, circuit means for maintaining said checking relay energized between the polar energizations of said line circuit,

and additional circuit means for maintaining said checking relay energized during each polar energization oi said line circuit only if the corresponding signal control relay positions itself properly in response to the polar energizations of said line circuit.

4. In a centralized traiic controlling system for governing the operation of signals associated with a track switch at a distant field station from a control orlice, a stepping and control line circuit extending from said oiilce to said station, a neutral relay responsive to the energization of said line circuit irrespective of the polarity of such energization, a series of stepping relays controlled by said neutral relay and energized sequentially, a polar line relay in said line circuit, two neutral signal control relays respectively governing the clearing of signals in opposite directions over the track switch, an energizing circuit for each of said signal control relays including a Contact of a particular stepping relay and a contact of said polar line relay, a checking relay acting if deenergized to open said energizing circuits, means for energizing said checking relay prior to the control of said signal control relays, stick circuits for said` signal control relays closed when said checking relay is energized, circuit means for maintaining said checking relay energized between the polar energizations oi said line circuit until the end of an operating cycle, additional circuit means for maintaining said checking relay energized during each polar energizations of said line circuit only if said signal control relays in turn position themselves properly in response to the polar energizations oi said line circuit, a detector track circuit, and stick circuit means rendered eifective upon deenergization of said checking relay and governed by saidfdetector track circuit for sticking up an energized signal control relay.

5. In a centralized traffic control system for governing the operation of a power-operated track switch and the indications of associated signals, a communication system for transmit- `ting frorna control omce to a field location a switch and signal control code oi code elements of different character, step-by-step apparatus at the eld location operating to assume a new step position for eachioi said code elements, a switch control relay and 'a signal control relay rendered responsive in the order named by the operation of said stepby-step apparatus to the character of the successive code elements in the switch and signal code being transmitted, checking means rendered effective only if said switch control relay assumes a condition'in conformity with the character oi the switch control code element, and a control circuit for a signal control relay opened when said checking means is ineffective, whereby failure of said switch control relay to respond properly to the switch control code element transmitted prevents subsequent control of the signal control relay.

6. In a centralized traiTc control system for governing `the operation of track switches and associated signals on railroads, a communication system of the code type including apparatus for receiving successive code elements of a variable character in a control code for governing the operation of a switch and its associated signals, step-by-step apparatus operated to a diiferent step position for each of said control code elements irrespective of its character, a plurality of control devices one for each step for governing said switch and signals, a checking stick relay, control circuits for each of said control devices prepared when said step-by-step apparatus assumes a corresponding step position and only if said checking relay is then energized, means for momentarily energizing said checking relay when the iirst of said code elements is transmitted, and stick circuit means for maintaining said checking relay energized only so long as each of saidcontrol devices on each of the successive steps assumes a condition in conformity with the character of its respective code element.

7. In a code communication system for centralized traflic control systems for railroads, apparatus for receiving successive code elements of a variable character in a control code comprising, a bank of stepping relays operating to take one step for each of said code elements irrespective of its character, a plurality of control devices one for each step rendered eiective in succession by the operation of the relays of saidstepping bank to respectively respond to the character of the successive code elements transmitted, and means acting automatically whenever any one of said control devices on any step fails to conform with the character of the code element transmitted for that step to prevent response of the control devices for any subsequent step, whereby the failure of any control vdevice to properly respond to the character of its respective code element discontinues the reception of any subsequent code elements for the remaining control devices.

8. In a code communication system. for centralized trafiic control systems for governing from a control oflice the position of a power operated track switch and the indications of the associated signals, apparatus at the eld location for receiving and storing the switch and signal control codes, a line circuit connecting the control oilice and the eld locations, a polar line relay at the eld location operated in accordance with the polarity of the successive impulse energizations of said line circuit in accordance with the switch and signal control codes being transmitted, a bank of stepping relays governed by said polar relay and operated to a new step position for each impulse on said line circuit irrespective of its polarity, a plurality of switch and signal control devices one for each step rendered controllable by the operation of said stepping relays to the polarity of energization of said polar line relay on the successive steps, and means for discontinuing the control of said control devices by said polar line relay if any devices remain to be controlled Whenever a control device on any step fails to conform with the polarity of the energization of said line relay for that step.

9. In a code communication system for railroads, code receiving apparatus for a eld location comprising, a polar line relay distinctively operated during successive steps in an operating cycle in accordance with the polarity of the successive code elements of a control code, a stick checking relay, step-by-step means governed by said line relay to take a step for each code element irrespective of its polarity, a plurality of control relays one for each of said code elements rendered eiTective in turn by the operation of said step-by-step means to be controlled by the operated condition of said line relay only if said check relay is then energized, means for momentarily closing a pick-up circuit for said checking relay prior to such control steps, and stick circuit means for maintaining said checking relay energized only if each of said control relays on the successive steps in turn matches the then existing condition of said line relay, whereby failure of any one of said control relays on any step to follow the code element transmitted automatically discontinues the reception of any subsequent code element by the remaining control relays, if any.

10. In a centralized traflic control system, apparatus for receiving and storing the successive elements of a control code comprising, line relay means responsive to the character of each code element, a bank of stepping relays governed by said line relay and operated to a new step position for each code element, a power-operated track switch and associated signals governing train movement over said switch in both directions, a switch control relay for governing operation of said switch, two signal control relays for governing the clearing of a signal for one direction or the other, circuit means for rendering said switch control relay and signal control relays responsive in the successive positions of said stepping bank and in the order named to the condition of said line relay means as established by the character of the corresponding code element then being transmitted, and means operating for any one of said step positions of said stepping bank if the switch or signal control relay for that step position fails to conform with the code element being transmitted for discontinuing control of the control relays for any subsequent step positions, if any.

l1. In a centralized tramo control system for governing the operation of a power-operated track switch and the indications of signals governing train movement over said switch in both directions, a line circuit energized with timespaced impulses of one polarity or the other in accordance with a control code for governing the position of the track switch and the clearing of a signal for one direction or the other over said switch, a polar line relay in said line circuit, a bank of stepping relays operated to a different step position for each impulse on the line circuit irrespective of its polarity, switch and signal control relays for respectively governing the operation of said track switch and the indications of the associated signals, a checking relay, means effective for controlling said switch and signal control relays in turn and in the order named during successive stepping positions of said stepping bank in accordance with the condition of said line relay, said means being effective for said signal control relays during said successive steps only if said checking relay is energized, and means for deenergizing said checking relay on any step if the control relay for that step fails to take a condition matching that of the line relay.

l2. In a centralized tralc controlling system for railroads, a power-operated track switch and signals governing train movement over said switch, apparatus for receiving and storing the distinctive character of successive code elements transmitted from a distant control oice to govern the position of said switch and the indications of said signals, said apparatus comprising, a bank of stepping relays operated to take a step for each code element irrespective of its character, a switch control device for one of said steps having two windings, said switch control device having contact means remaining in the position to which it is operated by the energization of one or the other of said windings until changed by the energization of the other windings, means governed by said stepping relays for energizing one winding or the other of said switch control device on a switch control step in accordance with the character of the corresponding code element transmitted, a checking relay energized only if said contact means of said switch control device assumes a petition in accordance with the character of the code element being transmitted, signal control. means, and means for governing said signal control means on a succeeding step in accordance with the character of a signal control code element only if said checking relay is then energized, whereby failure of said switch control device to respond to a switch control code being transmitted prevents operation of the signal control means.

13. In a centralized traffic controlling system for railroads of the type described; a control line circuit extending between a control oice and a remote eld station over which control codes are transmitted, each code including a series of code elements of controllable characters; step-by-step means at the eld station operable to take one step between each element of a control code; a plurality of neutral control relays, each associated with a particular step of said step-by-step means, and each having a pick-up circuit energized or left deenergized on that stepdependent upon the character of the code element for that step; a checking relay allowing said pick-up circuits to be energized only if such checking relay is picked up; circuit means for picking up said checking relay at the beginning of a series of code elements; a rst stick circuit for said checking relay closed between successive code elements while said step-by-step means is being operated to take the next step; a second stick circuit for said checking relay closed during the presence of a code element on said control line circuit for any given step only if the control relay for that step is in the position corresponding to the condition required by the character of the code element for that step; stick circuits for said control relays closed by said checking relay while it is picked up; means effective at the end of a control code for deenergizing said checking relay and causing said stick circuits for said control relays to be shifted to stick bus only providing a proper number of code elements have been received to complete the control code, and means for at times deenergizing said stick bus, whereby those of said neutral control relays which are picked up, are then deenergized.

14. In a control system for governing from a control oiiice the operation of a track switch and its associated signals at a distant eld station by the transmission of control codes having positive and negative code elements over a control line circuit connecting the control oflice and field station; a polarized line relay included in said line circuit and distinctively responsive to said positive and negative code elements; a neutral relay energized in response to the energization of said polarized line relay irrespective of the polarity of such energization; a series of stepping relays controlled by said neutral relay so as to be sequentially energized one relay for each deenergization of said neutral relay; a series of control relays for governing the operation of said switch and signals, each relay respectively associated with one of said stepping relays and distinctively controlled in accordance with the positive or negative characteristicy of the code element for that step; a checking relay allowing the control of said switch and signal control relays only if it is energized; means for energizing said checking relay at the beginning of a series of control code elements; stick circuit means for said signal control relays closed when said checking relay is energized; stick circuit means controlled by said neutral relay for maintaining said checking relay energized between the code elements of a series while said neutral relay is deenergized; a selective stick circuit for said checking relay energized during each polar code element of a series as repeated by said line relay only if the control device for that step takes a position corresponding to its control by said polar line relay; a detector track section associated with said track switch for controlling a track relay; and means effective at the end of a control code to cause the ydeenergization of said checking relay and the transfer of the stick circuit control for said signal control relays from said checking relay to said track relay, said transfer being effected only provided the proper number of code elements in the series are counted off by said stepping relays.

15. In a switch and signal control system for railroads; a control line circuit connecting a control office and a field station and having different control codes applied thereto comprising series of distinctive code elements to govern the position of a switch and the indications of a signal located at the field station; a series of stepping relays at the neld station operated successively one at a time foreach code element on said line circuit; a switch control relay of the twoposition magnetic stick type for controlling the power operation of the track switch, said relay being associated with a particular one of said stepping relays; a neutral signal control relay for controlling the clear and stop indications of the signal, said signal control relay being associated with a subsequently operated one of said stepping relays; a detector track relay associated with said track switch; and circuit means controlled by said stepping relays and the distinctive code elements on said line circuit so as to position said switch control relay in one or the other of its two positions in accordance with the character of the code element for its step and so as to cause said neutral signal control relay to be picked up or deenergized in accordance with the character of the code element for its step, said circuit means being eiective to pick up said signal control relay only if said switch control relay operates to a position corresponding to the character of its code element; a stick circuit for said neutral signal control relay including a front contact of said detector track relay; and circuit means controlled by said signal control relay in a picked up position for clearing the signal; whereby the signal can be initially cleared only providing said switch control relay properly responds to the character of its code element. l

16. In a centralized traflic controlling system for railroads of the type described; a control line circuit extending between a control oflice and a remote field station over which control codes are transmitted, each code including a series of elements of controllable characters; a power operated track switch with signals for governing traffic in opposite directions thereover; step-bystep means at the field station operable to take one step between each element of a control code; a switch control relay of the two-position magnetic stick type for governing the power operation of said track switch, said switch control relay being associated with a particular step of such checking relay is rendered active; circuit means for rendering said checking relay active only if said switch control relay operates to the proper one of its two positions corresponding to the character required by the code element receiVed on its particular step; a detector track circuit associated with the track switch and having a detector track relay; and stick circuits for said signal control relays including a front contact of said detector track relay.

ROBERT F. WELLS. 

